[moderation] [fs?] KCSAN: data-race in do_sendfile / ksys_write (16)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 71b1543c83d6 Merge tag '6.9-rc5-ksmbd-fixes' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f01d9f180000
kernel config: https://syzkaller.appspot.com/x/.config?x=4128b708dfac799b
dashboard link: https://syzkaller.appspot.com/bug?extid=4a5812884a6bf667caf2
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8b58054f3198/disk-71b1543c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/50c92527b69a/vmlinux-71b1543c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f9cb9354fd63/bzImage-71b1543c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4a5812...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_sendfile / ksys_write

write to 0xffff888104341740 of 8 bytes by task 23264 on cpu 0:
do_sendfile+0x787/0x970
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
x64_sys_call+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888104341740 of 8 bytes by task 23263 on cpu 1:
ksys_write+0x11e/0x1b0 fs/read_write.c:645
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
x64_sys_call+0x27b7/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0x0000000000260000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23263 Comm: syz-executor.0 Tainted: G W 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================


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